Into the Nest: Home, home on the range (bobolink style)
Everyone loves the crazy bobolink. Their backwards tuxedo, blond mullet, and R2D2 song are whimsical and memorable. I enjoy thinking about everything a bobolink has seen during its long migration between Wisconsin and South America, and admire its amazing twice-yearly trek.
Bobolinks are polygamous,which is a mating system where one male may have multiple female mates. Females select their mates based on the quality of territory, song, and flight display. Dominant males with the highest quality territories will maintain pair bonds with several females, while subordinate males may bond with only one female or be unsuccessful in finding a mate.
Bobolinks hold multipurpose territories where they forage, court their mate(s), and raise their young. In Wisconsin, bobolink territories range from 0.7 to 2 ha depending on the habitat quality (Martin 1971; Wiens 1969). Males compete fiercely for territories using song, displays, aerial chases, and sometimes physical fighting. When displaying, males will perch on a conspicuous piece of grass or a flower and sing. They hold their wings slightly out from their body, lower their head emphasizing the light yellow color, and flare their tail to show off their rump patch.
They have an especially lovely flight display. Usually when a male flies, they flap their wings so that they almost touch at their highest point, and are silent. When displaying, they fly in slow, looping arcs over their territory. Their flight pattern changes drastically, with their wings barely reaching horizontal at their highest point. They sing their bubbly song as they fly a loop around their home, usually crashing to perch on a grass or flower stem. Males continue to defend territories until they begin feeding chicks- at this point, territory boundaries begin to dissolve.
Male bobolinks will chase females around their territories as part of their mating rituals and pair bonding. Females are generally tolerant of their male’s other mates, and won’t chase them off of their territory (Renfrew 2015).
Martin, S. G. 1971. Polygyny in the Bobolink: habitat quality and the adaptive complex. Phd Thesis, Oregon State Univ., Corvallis.
Wiens, J. A. 1969. An approach to the study of ecological relationships among grassland birds. Ornithol. Monogr. no. 8:1-93.
Renfrew, R., A. M. Strong, N. G. Perlut, S. G. Martin, and T. A. Gavin (2015). Bobolink (Dolichonyx oryzivorus), version 2.0. In The Birds of North America (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.176